Heyas,
BE-76 - Nice to fly. VERY Docile, and a GREAT panel layout for steam gauges. Electric flaps. Doors on both sides, if that matters to you (no crawling over the seats). Unfeathering accumulators.
They are getting hard to find on the rental line, and most have wound up as private birds.
PA-44 (pre-90) - I actually preferred the way -44s handle over the Duchess, and they are stone simple. Manual flaps, but none of the pre-90 versions have accumulators. Panel layout is ok, but nowhere near as good as the Duchess. Gonna be hit or miss on the avionics some had HSIs, some didn't, some had APs, some didn't.
This era Seminole has a turbo version, if you are doing training at a high DA. I think they built 80 or so turbos.
Most from this time (78-81)have been rode hard and put away wet. They were THE training airplane until Piper started to ramp up PA-44 production again with the new metal panels and/or glass layouts. Heck, I flew a '81 model in '91 that had 10k hours THEN.
PA-44 (post-90s) - Good airplanes. Accumulators and modern avionics. $$$
PA -34 Seneca - Depends. More expensive than -44 or a BE76 due to the turbo. IIs had manual wastegates, which were an unnecessary distraction for the newbie. IIIs and later had auto wastegates. Insurance is high, but probably not has high as others.
310s - Complicated fuel system. Rs were bad-a$$, but a handful for for the newb. SPENDY for gas.
Grumman Cougar - IF, and that's a big IF... you can find one to rent. VERY docile. Cheaper than a -44 or BE76 because it used O-320s vs -360s, but had the same performace. Think of it as a totally nerfed Comanche...same economy, but MUCH simpler and easier to handle. Rare even when they were made, I can't imagine there are any to rent.
Aztecs/Apaches/BE95s. All will likely have a hodge podge panel. Apaches have sometimes goofy systems (Hyd gear and flaps, but only one engine has a pump) and performance is very meh. Expensive upkeep.
Nu