250 is all you need. (honestly for what we do a 150 is more then enough)

I had a 250 Transit Diesel (had to get rid of it because of city ordinance) I bought that because I had big plans of building it out and it was going to way a ton.

There isn't a huge difference in ride quality between a 150 and 250. Get the 250, don't even bother thinking about the 350. We honestly don't carry around a lot of stuff that weighs a lot.