I've been through dozens of lamps over the years, and I've possibly forgotten a lot of the features and attributes, but here's what I remember and what has struck me as good enough to keep. There's a trade-off between the size of the reflector: the bigger it is, the better the quality of the beam, generally speaking and the smaller it is, the less the wind catches it and blows you about off aim.
For foxing or running dogs the Deben Tracer Max is excellent, good penetration, good beam quality and it's not too heavy and it's tough. It's also small enough not to act like a sail when you're shooting in a wind, which is one criticism I have of the Lightforce 170, along with its beam quality not being as good.
For air rifle use I think the Deben Mini Pro is an excellent choice, although the red filter is flimsy and leaks white light.
My favourite for air rifle work is a Gunlamp 400, in a modified state. I removed the coiled lead and switch (which weighed almost as much as the lamp itself) and replaced it with a Deben dimmer switch and cable. This now has the penetration to see where bunnies are on an East Anglian prairie, a good enough beam quality and it's as light and tough as anything in the business.
For shooting in enclosed areas and on small fields where you might know exactly where your prey is, the Tracer Atom, Logun and Nite Hunter might suffice; I've owned them but they weren't for me. I also find stock-mounted batteries a solution looking for a problem to solve; they put weight where you don't want it and the power is limited, and there's a price penalty. I find it far better to carry a small SLA in a pocket or cartridge bag.
Something I haven't tried yet are these new LED lamps like Deben's LEDRay or Tracer Stinger. If they really do the business I'll probably go for one as they are so small, but while I've lashed out 50 or 70 quid out of curiosity in the past, I've got things that work to my complete satisfaction at the moment so I'll wait until I see one in action first.
"Everything not invented by God is invented by an engineer." HRH Phil the Greek.