Blackwood Outdoors have Infiray Finder FH35R V2 brand new for £1400... the spec on those is better than anything else you can get new for the money and you get a warranty (wherever used it can be wobbly terms) and that's a fact. No other brand will give you 640 and rangefinder for that money and If you don't believe me, speak to Ian Blackwood himself, who tests all the brands and names. I myself have been using thermal of different brands in the field since 2016, just as a someone who does foxing and stalking.
This is because it's 640 resolution and has a rangefinder, anything else new for that money will be 384 or 320, so half the detail/more blur to what youre looking. Good magnification, good Net D - so heat shows well, the lower the NET D number, the higher the sensitivity.
The competition from Hik on that would be the Condor CQ35L Pro at around £1900, basically same spec on paper and you won't see a great deal of difference by eye. Pulsars competition on that would be a Axion 2 XG35 lrf , £2600.. I love those units myself and have a Pulsar bias as they are high quality and honest products but is it worth another £1200 over the Infiray, I say no.
The Infiray also has a F 0.9 35mm lens, the other two have F 1.0. Technically the F0.9 lens let's in more heat radiation.
Whatever you do, Ignore Zeiss altogether, you are only paying for the name. The specifications of the technology you pay for, is less money with competitors that know the technology better and they have been doing it longer. They aren't bad but you pay more for no reason. I do love Zeiss scopes, they are great at optics but they just jumped on the band wagon for the money when it comes to thermal imaging.
I hope that helps.