Smaller aircraft are great because they allow you to win on frequency, however in terms of long term profitability i'd stay away.
Smaller aircraft have the same (or close to) fixed costs as a larger aircraft, which really does impact their profitability. Say we compare an A321 and an E195. They both pay similar landing fees, navigation fees and the like however the E195 can have up to 100 less pax. That means you've got 100 less pax to pay nearly the same fixed costs, it just doesnt make financial sense.
Props are great. Not so much now because of the dirt cheap fuel price, but later in the game is where they really come into their element. really the only decent props out there are the Q400 and the ATR 72s in my opinion, especially the Q400 because of its jet like speeds on short sectors.