I have both the 436HP and WS1080. Both very good radios. Each with plus and minuses. 1080 probably a bit better on VHF sensitivity. 436HP hands down better on multisite trunk system programming where you want to be able to switch on/off different sites. Can be done with 1080, but much more cumbersome. On the fly changes/programming much easier with 436HP.
In Los Angeles, I find 436HP handles weaker P25 decode much better than 1080. Has to be fairly strong for 1080 to decode without Donald Duck sound, whereas 436HP can decode P25 on signals that don't even move the RSSI bar meter.
A big issue for me is third-party software for logging and virtual control. Does not exist for 1080 or its cousin the RS668, as far as I know. For the 436HP, like the 536HP, there are software choices. Both have record. 436HP records all hits if you press "record," 1080 will "record" only channels you designate. However, 436HP has "replay" function, whereas 1080 does not (AFIK). I use the "replay" feature all the time if hear something interesting, but missed what channel/TG because I was looking elsewhere, for example, the road in front of me. 436HP will replay and show all information.
For me, if only had one, would definitely be the 436HP. I'm sure others have different opinions.