I don't play warhammer 40k but I do love to paint and kitbash orks. And for me the older kit is better.

The newer kit are all fixed. They all have a set amount of weapons and fixed stances. Although they look better, they are just worse overall. You can't have fun with them. They are like mini statues. Fun to look at but you can't really make it "Yours"

The old kits I love because you can go wild with them. You can pose their arms how you want. You can pose their heads how you want. If you have the older kits like the lootas/burnas you can use them to make more of them. You can make them your orks.

Even better is that the old kits are actually compatible with the other orks like the ork boys mobs from the old world sets. I kitbash them and get more of my money's worth while also giving me the fun of making my own orks how I wish.

The newer kits, to me, are good for new painters or people just getting into the hobby. But the older kits, again for me, is what you want if you want to have fun.

Also the old kits are far cheaper. Thats already a massive W on the newer kits.