I totally agree with Nitro here. I think anyone who has deeply researched and analyzed that topic has very probably learnt a lot on trading.
Now as many things in that area, I believe there is no sure answer. Then, it's all again a matter of personal preference, but here is my shot.
Most of the time I hit the offer to go long and the bid to go short. I'll try to give some of my reasons.
I'm a full time trader. The mini Russell is my favorite playground. I'm also mostly a trend follower : usually try to take a couple nice moves per day (which could be moves as much as 2-4 points). But I also scalp for a few ticks to play reversals or range trades and thing is I never really realized the importance of the lmt/market order question until I got interested in very short term trading. And that brought significant changes to every aspects of my trading strategies.
Now, whether I scalp for a few ticks or aim for a longer target, my entries are almost the same. I'll go with the flow and want the market to keep going in the same direction right after I got in. When I hit the offer to go long, I expect immediate orders to eat the remaining offers and the bid to raise at my entry price. I will allow very thin adverse reactions, if none, because I have a reason to be in. When I place my order, I expect momentum.
Buying the bid or placing a buy lmt below the bid and then waiting to get filled is like expecting a "retracement" to get in.
If your sitting lmt order gets filled it simply means that the micro short term momentum goes against you and that you're in "trouble",
at least in that micro time frame.
Searching an answer to that question, you will most likely end up studying market depth dynamics and games, orders flows.
And that journey is definetly worth it...
Ludovic