I have had accounts with both.
Depends on what you want to trade and when you want to trade it. With IB you can trade much more securities at all times of the day.
With MB, there is less offered to trade, and they limit the hours.
It also depends on if you care about customer service. And please note, I wouldn't call needing to call customer service in a crisis being in need of handholding. When a crisis arises, that is when a firms true colors come out. And with all of relying on technology, you never know when you may need help. My experience with IB customer service has been terrible.
MB on the other hand has outstanding customer service. From opening an account,to calling the trade desk to check on trades, they answer the phone promptly, act like they care if you have a problem, and actually resolve things in a timely and professional manner. Wish IB did the same, but they didn't with me, and they lost a customer because of it. Being able to get out of a trade quickly is well worth the small difference in commison.
Also, it depends on how much you trade and what you trade, ie, how much difference IB's cheaper commissions mean to you.
I occasionally trade stocks, but mostly Eminis and not heavy volume. For me, the difference in commissions doesn't warrant putting up with the attitudes at IB, so I much prefer MB.
Also, there is a recent thread discussion MB's vs. IB's interest rate on your account. Seems like for many, MB's better rate may cover the difference in commissions.
As for front ends, I think IB has more. I think TWS is an embarrassment, but there is a lot more that IB integrates with. More than with MB I think, certainly with futures. MB's only DOM style interface is Ninja, and while I like the features, it feels pretty buggy these days. Wish MB would consider partnering with others with DOM style interfaces, I would think it would broaden their customer base.
In any case, there is pluses to minuses to both, and it is a personal choice. And again, really depends on what you are going to trade, when you plan to trade it, and how much of it you will be trading.
Those specific considerations aside, I wouldn't hestitate to recommend MB Trading, I am very happy I switched from IB.