My opinion is: your photos are very cute & I’m just thinking of these photos on display being enlarged, not that I don’t like them, but for what you’re wanting them for…
Not #1 (unless you crop out the person in front of you, they take up most of the photo & if you crop, it will cut off too much of the photo)
Not #2 (beautiful picture, but there’s not much contrast so you blend in to the background)
Not #3 (your FI’s head is cut off)
YES to #4 & I’d make it one of the bigger ones (if its small, you’ won’t be able to see you & your Fiance very well)
Yes to #5 (so cute! you can see your personalities & that you’re having fun)
No to #6 (your eyes are closed & its an awkward angle)
Yes to #7, its cute but would keep it as a 4×6
Yes to #8 (this one is georgeous with the orange trees & the lighting)
Yes to #9 as a 5×7, I like the background but the lower part of the photo makes it too busy, but if your photog can crop the photo (get rid of the bottom 1/3 & the left 1/3 of the photo, I think it could be made as an 8×10.
Yes to #10 & that could be enlarged, very cute 🙂
#11 is cool, but you can’t see your FI’s face at all… the background looks a little blurry, but I would keep this one as a backup for a 4×6
#12 keep in color! & yes, I would pick this one as a 5×7 or larger
#13 only as a 4×6, its cute but its blurry
#14 as a 4×6, you both look happy there 🙂
#15 as a 4×6 or 5×7
#16 as a 4×6 or 5×7 (lol I love the duck in the upper right hand corner)
#17 looks very romantic, slightly out of focus so would keep that as a 4×6 or 5×7
No to #18, the tree is right behind him & its not very contrasty
#19 is adorable but you’re looking away & he’s not, my preference is no on this one, but its a great shot.
No to #20
& #21 looks like #14 to me.
ETA: I looked @ #4 again but it looks like you both are out of focus & the arch is in focus, so I wouldn’t enlarge it if that’s the case. I would make it a 8×10 if you’re out of focus, because its really pretty & you can tell who you guys are.
For sizes I say:
Enlarge #5, #10 as the 2 largest pics
#4 & #12 as the 8×10
Not sure how many 5×7, but I’d say: #8, #9, #16 & #19
& for 4×6: #7, #11, #13, #14, #15, #17