Shank! If you don't mind cooking it for a while, the shank has some of the tastiest meat for long, moist cooking. If you can get it sliced like an osso buco you can throw the bones in with it. The marrow adds so much to the body of a stew. I use lamb shank a lot for stew as well, sliced into 1" pieces on the bone.

I'm with flgal on this -- chuck roast (or arm roast, or shoulder roast, as some groceries/butcher shops will label it). I buy two or three when they're on sale and freeze them. They're my go-to for soups and stews and braises.

If you can find it, boneless short ribs would be good too. The butcher will have boned the short ribs, but you can cut then cut them into whatever size cubes you want

I've also found that the meat labeled "beef stew meat" or something like that is never as tender or flavorfull as the beef chuck that I've cut up. I think it must be random pieces and parts.

I definitely go with chuck for stews but occasionally will use beef cheeks or boneless short ribs and get fantastic results.

I'll join the shoulder choir. It works well in stews and is easy to cut up.

You know we really like to get a thick cut sirloin and cut it up for stew - our butchers are great bout helping us get the best available, so we'll have them cut us a thick steak or two and we take it from there. As an aside - Mr L grills a LOT of steaks, and we save the bones and make grilled steak bone stock which leads to some excellent stew ....

I agree with flgal, ask for a "roast" (chuck or shoulder) and cube it yourself. If you have a good butcher, perhaps they'll lead you in the direction of what is freshest.

I buy a chuck roast and cut it up myself.