I have both .177 & .22 in the HW45, my brother has an HW70. All of them are extrmeley well built and should last a lifetime.
All are extremely accurate, but the HW45's are far more "lively" due to the fact they are springers, so require practice on your stance and grip.
I'm right handed, so use a "triangle" hold, with my right arm straight and my grip very loose, while pulling back with my left hand, which produces good results, the .177 is the livelier of the 2, but is very accurate if used on half power, as there is the ability to choose half or full power when cocking.
The HW70 is completely recoiless and is very accurate indeed, really depends on what you want to do with it, if it's predominantly targets, the HW70 is ideal, if it's skipping tin cans down the garden from 10 to 40 yards, I'd choose the HW45 every time.
Hope this helps
Paul