Aggressive, live, electric blues.....

After the recent Zep live 3 disc set, Hendrix at Berkeley 2nd show, and Allman Brothers Fillmore other legendary live shows with stellar sound that come to mind...waiting for the remaster of Hendrix's Live at winterland...SRV live maybe?
SRV's DVD "Live from Austin Texas" is a fascinating disc. It
isn't the best quality recording you'll own, but the performance is true
Stevie Ray, and the contrast between the two shows...performed during
his alcohol/drug days and after his chemical days... are astounding. The
insecure performer of the early show, who cannot look at the audience,
is replaced by the confident, clear-eyed performer he became in his later
years. Both concerts burn.

Man, I miss this guy.

Walter Trout and the Radicals - Relentless

Live from Amsterdam. This guy can play! All new material preformed live at his favorite club. Extras are great as well.
Joe Bonamassa,"So It's Like That".Get the cd that has the
bonus live DVD.The DVD is killer stuff!Also pick up Rory
Gallagher, BBC Sessions.A great collection of material
recorded in front of an audience and live in the studio.
Not sure of your definition of "aggressive", but I nominate Johnny Winter Live in NYC 97'
Jimmy Thackery: Wild Night Out

There is a live Luther Allison collection from his career that is killer.

Ronnie Earl, Blues Virtuoso in Europe isn't exactly agressive but it is some amazing live blues guitar playing.

He don't have a live album but if you get a chance to hear Tinsley Ellis live you best not miss it. His studio stuff smokes. Try Storm Warning

I saw Joe Bonamassa live this summer. Thnak goodness it was a free show. My brother described it best when he compared the playing to someone posing for his own bedroom mirror. Not my idea of a blues player.
Also try Son Seals "Live and Burnin'" on Alligator. The first four tracks are pure smoke! The rest of the disk is quite good, too. Basically it's a set of power Chicago blues recorded in a smokey club in the 70s.