I need some help choosing a boat. I fish mostly ponds and small lakes (less than 500 acres). I will fish alone some and with a buddy some. I’m a big guy, over 300 lbs. I can’t afford a big bass boat. I have explored everything from kayaks, canoes, roundabouts, jon boats and others. Please share your thoughts on what might work for me. 

What do you consider big?  15', 18', 20+'?  There are plenty of aluminum boat options that would probably work for you the types of water you fish. G3, Xpress, Alumacraft, Alweld, etc.  Also, are you looking to only buy new, or would you consider used? 

I fished out of a 14' flat bottom for 16 years. I put a floor in with carpet, started out with a transom trolling motor, then upgraded to a bow mount trolling motor. You can get them cheap used, even the new ones aren't terribly expensive. 

Take a look at the Crestliner lineup of open "Canadian" style tiller boats. One in the 16' - 18' range will suit you just fine and won't break the bank. These boats are the widest on the market, have plenty of room and are extremely stable crafts. Best part is, being open like that allows you can customize them to suit your needs. Also, a lot has to do with your budget restraints as well.

For the waters you describe, I would be perfectly content with a 14' X 48" jon boat with a trolling motor with a small outboard as an option.  

I'd go for a 16' 48" wide jonboat since you mention being a big guy. Also google up the Carolina Skiff J14 series. Basically a jonboat but fiberglass and can feel a tad roomier.

You never mentioned a budget.