well the equivilent to 40k's 1500 is 2000pts, and most people will like to play around that points value as it allows you to use a lord in the army. 1000 points is the usual start out value for "proper" games and under that its probably best to use border patrol rules.
I usually play 2000. It's common because it allows you to field and Lord character and a centerpiece unit such as a Dragon.
I've seen 1999 games for the opposite reason - you don't have Lords and can't field most monstrous mounts.
2250 is a good number. Most players will end up with that amount when they build to 2000 (rounding unit sizes, swapping out other units). It has the advantages of a 2000 point game but the extra 250 points allows each side to field another regiment of infantry or a small unit of Knights or a couple smaller missile units. It's a nice size because it's a little less focused on characters than 2000 but is still quick and easy to transport.
3000 is good for bigger games, but I find that the magic phase tends to fall apart a little bit because armies will either completely dominate or not be able to accomplish much at all depending on how their designed. Consultation in advance can mitigate this though. You'll also want a bigger table for 3000. Skaven, Orcs, and even infantry-heavy Empire will fill up a 6x4 table to the brink. With an 8'x4' table armies will still have flanks and maneuverability will remain an important element. You may consider adding an extra turn (7 turns instead of 6) to compensate for the larger play area.
1000 is the ideal size to learn the game. You can finish a game in under an hour once you learn the rules and there's unlikely to be too many special rules in play at any one time. The game tends to be a little luck dependent. You can only afford a few infantry units so if you roll bad on your break tests you can be wiped out in a single turn. Likewise if your one cannon or stone thrower misfires and destroys itself the first time it fires you can be disadvantaged. (Last game I played at 1000 both my Dwarf Cannon and my Empire opponent's Great Cannon rolled destroyed results the first time they fired, so it balanced out.)
Below 1000 points the game breaks down and the formation rules don't really make sense. You can put together 1000 points with a Battalion Box and a character or two, so I don't see much reason to go below that amount. (There are Chaos Warband rules, Border Patrol and Warhammer Skirmish for those that likely to build their armies a model at a time - I don't find any of them particularly satisfying personally.)
2000 is fantasy's equivalent to 1500 points of 40k-- it's sort of GW's standard, although people stateside tend to lean towards 2250 or 2500.
As Asmodai said, the game stops making sense at small points levels... really, the bigger the better with fantasy. It's not that hard to get to 2250 or 2500, either... a lord can easily cost upwards of 300 points, and if you take some of the more expensive options-- monstrous mounts and the like-- they can peak at around 600. It's usually good to have at least three characters when the points limit allows it, and I've found that really, the more the merrier. Unlike 40k, independent characters don't have to worry about a kill zone-- they can clear the front rank before anything else strikes, so you pretty much automatically win the combat. And then the accompanying unit just adds some more wounds in for good measure.
A forum community dedicated to Warhammer, Warhammer 40K enthusiasts. Come join the discussion about Warhammer and Wargaming collections, miniatures, tactics, terrain, reviews, accessories, history, displays, models, styles, scales, reviews, accessories, classifieds, and more!