Two categories to consider: (1) top-end talent, and (2) quality depth. Here's how, on a 1-5 scale (5 being best), I'd rank each position group as of right now - understanding that things can/will change.
QB
Top-end talent: 5 (Brady is elite)
Quality depth: 3 (Hoyer is a modest veteran backup and Stidham has ability but who really knows)
RB
Top-end talent: 4 (Michel is terrific, White is a phenomenal pass-catcher)
Quality depth: 4 (Harris a talented rookie, Burkhead is a do-everything player, and Develin a great blocker)
TE
Top-end talent: 1 (There's just no star to be found at all)
Quality depth: 3 (It feels like a group of useful players, all are capable of being helpful but none are great)
WR
Top-end talent: 5 (IF everything breaks right...Gordon is a stud, Edelman a SB MVP, and Thomas, if he comes back healthy, is still a top-level WR)
Quality depth: 5 (IF everything breaks right...Gordon/Edelman/Thomas/Harry/Dorsett/Harris/Berrios/Patterson offers a lot of versatility)
OL
Top-end talent: 4 (Thuney/Andrews/Mason are an elite inside OL group; Cannon, if healthy, is a pro-bowl caliber player)
Quality depth: 5 (Plenty of quality behind these guys, including the draft picks they just made)
Edge
Top-end talent: 4 (Bennett is still very good; Wise has lots of ability)
Quality depth: 4 (Winovich an exciting rookie, Simon can still play, Rivers has ability too)
Interior DL
Top-end talent: 3 (Guy and Pennel are solid)
Quality depth: 4 (A bunch of good players throughout this position group)
LB
Top-end talent: 4 (Hightower is back to being a stud; Van Noy a solid jack-of-all-trades)
Quality depth: 4 (Addition of Collins, return of Bentley, along with Roberts and maybe Sam)
CB
Top-end talent: 5 (Gilmore an All-Pro, Jackson is terrific, JMac a solid vet)
Quality depth: 5 (Williams a talented rookie, Jones is solid, Crossen is talented, Dawson and Webster still in the mix too)
S
Top-end talent: 4 (DMac still a quality player, Chung is outstanding)
Quality depth: 5 (Harmon may be the best #3 safety in the NFL, Melifonwu an intriguing talent, Brooks has some ability, and Jones proved he could play safety too)
Special teams
Top-end talent: 5 (Ghost and Slater among the very best at their roles in the NFL)
Quality depth: 5 (The Pats emphasize special teams play and they have tons of excellent core special teamers)
So putting this all together, I'd say that here's how the position groups rank:
1. Cornerback (5, 5) - Absolutely loaded
2. Special Teams (5, 5) - Terrific across the board
3. Wide Receiver (5, 5) - IF they are at full strength; if not, this ranking drops considerably
4. Offensive Line (4, 5) - Add in the best position coach in football
5. Quarterback (5, 3) - Brady needs to stay healthy; if he does, then this moves to the top based on how important QB is to a team's success
6. Safety (4, 5) - Nice infusion of youth to complement star veteran leadership
7. Running Back (4, 4) - Quality, depth, and versatility
8. Linebacker (4, 4) - Addition of Collins and return of Bentley really could help a ton
9. Edge (4, 4) - If Winovich meets high hopes, this group could be dominant
10. Interior DL (3, 4) - An unspectacular, but solid, group
11. Tight End (1, 3) - Still could use some help here, and I think they'll be fine when all is said and done, but definitely the weakest position group on the team
QB
Top-end talent: 5 (Brady is elite)
Quality depth: 3 (Hoyer is a modest veteran backup and Stidham has ability but who really knows)
RB
Top-end talent: 4 (Michel is terrific, White is a phenomenal pass-catcher)
Quality depth: 4 (Harris a talented rookie, Burkhead is a do-everything player, and Develin a great blocker)
TE
Top-end talent: 1 (There's just no star to be found at all)
Quality depth: 3 (It feels like a group of useful players, all are capable of being helpful but none are great)
WR
Top-end talent: 5 (IF everything breaks right...Gordon is a stud, Edelman a SB MVP, and Thomas, if he comes back healthy, is still a top-level WR)
Quality depth: 5 (IF everything breaks right...Gordon/Edelman/Thomas/Harry/Dorsett/Harris/Berrios/Patterson offers a lot of versatility)
OL
Top-end talent: 4 (Thuney/Andrews/Mason are an elite inside OL group; Cannon, if healthy, is a pro-bowl caliber player)
Quality depth: 5 (Plenty of quality behind these guys, including the draft picks they just made)
Edge
Top-end talent: 4 (Bennett is still very good; Wise has lots of ability)
Quality depth: 4 (Winovich an exciting rookie, Simon can still play, Rivers has ability too)
Interior DL
Top-end talent: 3 (Guy and Pennel are solid)
Quality depth: 4 (A bunch of good players throughout this position group)
LB
Top-end talent: 4 (Hightower is back to being a stud; Van Noy a solid jack-of-all-trades)
Quality depth: 4 (Addition of Collins, return of Bentley, along with Roberts and maybe Sam)
CB
Top-end talent: 5 (Gilmore an All-Pro, Jackson is terrific, JMac a solid vet)
Quality depth: 5 (Williams a talented rookie, Jones is solid, Crossen is talented, Dawson and Webster still in the mix too)
S
Top-end talent: 4 (DMac still a quality player, Chung is outstanding)
Quality depth: 5 (Harmon may be the best #3 safety in the NFL, Melifonwu an intriguing talent, Brooks has some ability, and Jones proved he could play safety too)
Special teams
Top-end talent: 5 (Ghost and Slater among the very best at their roles in the NFL)
Quality depth: 5 (The Pats emphasize special teams play and they have tons of excellent core special teamers)
So putting this all together, I'd say that here's how the position groups rank:
1. Cornerback (5, 5) - Absolutely loaded
2. Special Teams (5, 5) - Terrific across the board
3. Wide Receiver (5, 5) - IF they are at full strength; if not, this ranking drops considerably
4. Offensive Line (4, 5) - Add in the best position coach in football
5. Quarterback (5, 3) - Brady needs to stay healthy; if he does, then this moves to the top based on how important QB is to a team's success
6. Safety (4, 5) - Nice infusion of youth to complement star veteran leadership
7. Running Back (4, 4) - Quality, depth, and versatility
8. Linebacker (4, 4) - Addition of Collins and return of Bentley really could help a ton
9. Edge (4, 4) - If Winovich meets high hopes, this group could be dominant
10. Interior DL (3, 4) - An unspectacular, but solid, group
11. Tight End (1, 3) - Still could use some help here, and I think they'll be fine when all is said and done, but definitely the weakest position group on the team