Three years ago, due to aging eyesight, I decided to go all-in on red dots and I've never looked back. (no pun intended).
I've tried many. Although I have one RMR (on a RAMI BD) and folks rave about their durability; I don't like the small window and bottom load battery. JMO But it's perfect for my RAMI BD. Yeah, Trijicon just intro'd the larger SRO, but I already have DPPro's.
DPPro is hard to beat. Just bought my 3rd and never a problem in many thousands of rounds. The warranty is LIFETIME, whether you're original owner or not. Super durable, top-load battery, big window, adjustments 'click' 1moa for precision adjustment, and there's optional elev and wind-age adjustable rear iron for perfect co-witness. If there's any complaint, it is a bit tank-like on a compact and requires tall irons to co-witness.
I also have over 7,500+ rounds on a Romeo 1 (2nd gen) on a 229 LEGION RX and it's still going strong, although I turn on/off manually don't use the 'Motac' motion activation and I get better battery life. I like that the excellent XRay3 irons mate perfectly with the optic for co-witness from the factory.
SIG keeps upgrading their Romeo 1: 1st gen, 2nd gen, 6moa, Romeo 1 Pro, and if my count is correct; with the intro of '2nd gen' Romeo 1 PRO next month; there's now been 5 versions. If you had one of the early ones you might not be too happy; but I think they're trying hard to raise the bar in factory optics-equipped. Probably smarting from the fact the US Military recently chose DPPro for M17 SIG 320 with optics. Ouch! Hence the new/improved Romeo1 Pro with same mount pattern as DPPro.
Also have 3 Vortex Venom and they've been very good too. Excellent warranty, I think it's the bargain among them.
Ohh, and there's the Shield RMS on my P-01. Had a devil of a time getting it to zero at 10 yards because not enough elevation adjustment. Broke two and had to return to UK to get fixed; before I added a 1 degree Delrin shim to get enough tilt. The good news is it's working nicely now, 2,000 rnds since 2nd one came back from UK, and it's small and low enough to sit between factory sights to co-witness perfectly! However, I don't dare mess with the elevation adjustment for fear of breaking again.
If I had it to do over, I'd use the Venom on the P-01 and be done!
That's my 2 cents. -Vinny