I've tried practically every single kind of bot. Whether you benefit or not depends on what you are aiming for. Bid bots are basically like advertisements. You are very likely to loose money but if you spend enough, you'll get massive exposure. @smartmarket and @minnowbooster are more safer options with guaranteed profit under stable STEEM prices although their availability of votes is all over the place.

Resteem bots are hit or miss. sometimes they create some great exposure. Sometimes they do practically nothing. Bots like @tipu have their own kind of flavor. Basically it's all subjective. For pure exposure at the cost of money, you can't go wrong with bots. If you want to profit, then don't rely too much on bots. You might actually end up loosing money.