We liked both the 3011 and the 3051 but ultimately chose the 3011.
For the 3011 we like the large kitchen counter. We also like that the TV is mounted on the wall and not on a swivel arm where it is more prone to being kicked as kids are on the bed above the cab. Also there's not a bad seat in the house for the TV, it can be viewed from the couch or the dinette and even from the over cab bed.
We like the fold out sofa bed, we have 4 kids so with 6 of us we have two kids above the cab, two on the sofa and my wife and I have our own bed in the back and we still have the table to make into a bed if we need it.
We like the large amount of under storage space (the most of all the Forest River class C's I believe). We like that the bedroom has windows on both sides of the bed and above it that open for plenty of fresh air and cross circulation plus the window out the back so it feels very open and has views out two sides.
And we ordered our 3011 with both driver and passenger swivel seats for extra seating. I don't think that the 3051 would make much sense to have two swivel seats since the dinette would block one of them so that limited extra seating by one.
For the 3051 we liked the large slide out and the extra room it gave to the bathroom and kitchen areas. We really liked the bathroom sink being in a large opening with plenty of room to move around, the under-sink laundry bag and the skylights. These were some of our favorite features of the 3051 but the 3011 had too many of the things we needed going for it.
Like you said it's a matter of choosing what is right for you. No matter what you can't go wrong with Forest River. Good luck with your decision, you'll be happy with either one.
2015 Forest River Forester 3011 DS - 2007 Dodge Durango Toad