And why....
Speed, Reliability, comfort. Interested in flying retractable gear airplanes and going to sell my Cirrus soon for one.
OK, now, back to the original question.
Bonanzas and Mooneys both come in different sizes. Bos have the 33, 35, 36 models and Mooney has the short, mid, and long body.
It sounds like you're coming from an SR22 based on your IO-550 comment, so let's compare apples to apples as much as possible and go with the A36 and long-body Mooney.
If you want Turbo, there are TN A36s, and the Mooney Bravo (1989-2006) or Acclaim (2007-present). If you want two front doors like the Cirrus, the newest Mooneys (Ovation Ultra and Acclaim Ultra) have that.
But, let's compare the normally aspirated SR22, A36/G36, and Mooney Ovation. All have IO-550s (except pre-1984 A36s, which had an IO-520).
Speed: All will cruise at 170 KTAS, though the Mooney does so with lower fuel burn - I burn 12 gph in the Ovation, the A36 will run 14-15 gph, and the SR22 in the upper end of 17 gph.
Reliability: You have a good idea of Cirrus' reliability and I don't. Beech has a good reputation, though they also have a reputation for expensive parts. I can't speak to either.
However, the Mooney is built like a tank. I've only ever had one maintenance-related cancellation, and that was due to a bad mag which would affect all three airplanes equally. The only Mooney-specific part I've ever had to replace was a landing gear bushing. Other than that, inspections, and regular maintenance, all of my maintenance dollars have gone to avionics, engine, and other non-Mooney specific parts.
Comfort: This is going to depend on how you're built and how many people you're taking with you. Cirrus did a good job here. Mooney is also very comfortable, with the caveat being the low seating position. My main problem with the Bonanza is that its cabin cross-section is pretty much a semi-circle at the top, so I bump my head on the "corner". The Bonanza's major differentiator is an extra two seats and a nice, big back door to get into.
Like I said, this really depends on how you're built and your pax. I would say the Mooney is most comfortable for 1-2 people, Cirrus for 3-4 (composite airframe allows for a wider back seat), and obviously Bonanza for 5 or 6 since being tied to the top of the plane is definitely uncomfortable.
Happy to answer any other questions you may have. Good luck in your search!