I bought a pair (package deal) of the Bosch 4.5's from Lowes on close out 18 months ago. They were about $80 (I'd have to check Quicken, low dollar purchases don't stick in my mind so well) and were replaced with a lower amp model, same cost, but 1 vs 2 for that same price. They don't get a ton of use, but when I use them, they often get near constant running for a long duration of time. I highly recommend them.
You mention paddle over locking button. I thought I liked paddle until I used one for a long time. It blows. A locking paddle would be great, or if you never leave it running for long durations. I often do, so locking is the WTG for me, and would be what Id recommend. Now as tool guys, I really recommend you have both... But I don't have the money for that, so my pair are locking button.
I should say I bought these because a brand new HF 4.5" started letting the smoke out after about 30min of undercoating removal. Scary. Crappy quality.
Dewalts, as mentioned, are also great, my old mechanics shop had one that was probably from the early 00's and it was trekking along just fine!