You can play stock campaign with LwAmi. After finish i recommend to change mod to RA and you will be able to play campaigns from 688 H/K and Sub Command. Stock DW campaign was never upgraded for RA and could be impossible to finish on some platforms (like first mission on sub)
This thread is wrong - because both main mods are good for single. Sentence: RA is good only for multiplayer is false. Currently RA is better for single player missions because it's still developed.
RA and LwAmi are completly different and people who aren't good players in RA says many myths about RA.
In my opinion both mods are worth to play. It will show you how the same game could be different with mods
RA is much closer to realism but also much more complicated (some game mechanics based on cleaver "code" solutions). Lwami greatly improves vanilla game in direction closer to Sonalysts vision.
If you looking multiplayer - only RA is currently played.
We play DW + RA every Friday and Saturday.