The early Seagal films, before he disappeared up his own arse and started believing he really used to be a CIA agent and/or SEAL, were rather good. He progressively used new MA techniques and styles throughout his early films.
Nico was the frist film to ever really showcase Aikido. Seagal kept it simple - kote gaeshi, irimi nage, and some weapons fighting, techniques from bokken using baseball bats. There was also some great tanto dori.
Hard To Kill was more of the same, with some jo dori against an attacker holding a shotgun.
Marked or Death further expanded use of the aikido syllabus, including multiple attackers, and here is a great sword fight at the end.
Out For Justice - his most basic and most violent film, with no plot getting in the way of the continuous pointless fights he gets into. Makes for a brilliant film. Includes a stick fight in a bar against Dan Inosanto.
Under Seige - his first major studio film. A bit too much guns and explosives, but some good MA, inlcuding a knife fight at the end with the bad guy, played by Tommy Lee Jones. Girl from Baywatch gets her kit off for no reason.
Under Seige 2 - more commando stuff, but still some great combat, and his first use of Jujutsu when the fight goes to the floor in a crowded train cabin.
After that it started to go downhill as he got fat and pretentious. There are still a couple of good ones.
On Deadly Ground - Michael Caine plays the bad guy. A good bar fight and use of slow motion to capture the moves. Let down by a tragic horseback jump with slow motion bobbing pony tail.
Exit Wounds - co starts DMX and Tom Arnold. His first use of wire work. That infamous scene in the nightclub where he puts ikkyo on a bodybuilder who powers out of it. Had he trained at STMA he'd have known the lock flows to counter this scenario.
