Avengers #103 and X-Men #60 - Shady Faces

1969: X-Men #60 Neal Adams - this is Judge Chalmers

And inspired by a master artist...
1972: Avengers #103 Rich Buckler - Quicksilver

Avengers #103 and #75 - Quicksilver Sequence

1972: Avengers #103 Rich Buckler


The above sequence is based on two separate panels from Avengers #75.

1970: Avengers #75 J. Buscema

        1970: Avengers #75 John Buscema

Avengers #103 and #75 - Classic Quicksilver

Pretty standard pose of Quicksilver running at superspeed.

1970: Avengers #75  John Buscema

1972: Avengers #103  Buckler

Avengers #102 and X-Men #57 - Quicksilver and Larry Trask: Profiles

1969: X-Men #57 by Neal Adams    Larry Trask 

 1972: Avengers #102 by Rich Buckler 
Quicksilver

Avengers #102 and #79 - Quicksilver and Vision Back to Back

1970: Avengers #79  J. Buscema

1972: Avengers #102 Buckler

Avengers #102 and #76 - Arkon and Vision Back to Back

1970: Avengers #76 J. Buscema 1972: Avengers #102 Rich Buckler

Avengers #102 and #58 - Double Vision

(Top) 1968: Avengers #58 - John Buscema
(Bottom) 1972: Avengers #102 - Rich Buckler

Another angle.

                              1968: Avengers #58 - Buscema           1972: Avengers #102 - Buckler                                           

Avengers #102 and #79 - Don't Fear the Grim Reaper

Classic Grim Reaper

(Top) 1970:  Avengers #79 - John Buscema

(Bottom) 1972: Avengers #102 - Rich Buckler

Avengers #101 and #56 - Captain America to the Rescue

(Top) 1968 - Avengers #56  John Buscema
(Bottom) 1972 - Avengers #101 Rich Buckler

Update!
In response to Silver Fox's comment, here's a Kirby image that I'd stumbled on some time ago. It's from Captain America #105 (1968) and when I first saw it I was immediately reminded of Avengers #56 (and by extension #101). However I think the lead time is just too short between Cap #105 and Avengers #56 (the Cap issue was on sale a mere month before the Avengers comic); I doubt Buscema had access to this image. Besides, it's a fairly standard composition. 

Anyway, here's the Kirby image from Cap #105:  

1968: Captain America #105  Jack Kirby

Cap, Bucky and Batroc - Captain America #105 and Avengers #106

1968: Captain America #105 Jack Kirby                                     1972: Avengers #106 George Tuska 

Karate Kids! Tales of Suspense #94 and Defenders #57

1967: Tales of Suspense #94 - Jack Kirby

1978: Defenders # 57 - George Tuska

Agent 13's Tales of Suspense karate chop sure looks familiar-- remember this? ;)

Kirby and Pollard: Fantastic Four #47 and #316

Inspired by? 

Top Panel: 1966, Fantastic Four #47  Jack Kirby
Bottom Panel: 1988,  Fantastic Four #316  Keith Pollard

Kirby and Tuska: Fantastic Four #66 and Iron Man #49

1967: Fantastic Four #66 - Jack Kirby              1972: Iron Man #49- George Tuska

The images in context 

1967: Fantastic Four #66                                        1972: Page 4 splash from Iron Man #49

More Kirby and Tuska here and here.

Behold the Vision! Avengers #57 and Marvel Two-In-One #39

Classic Vision stance! First, Vizh flexing some muscle in his debut in Avengers #57-- by Big John, natch...

1968: Avengers #57 - John Buscema 

...and here's Vizh in Marvel Two-In-One #39--Ron Wilson's version.

1978: Marvel Two-In-One #39 - Ron Wilson

The full Buscema panel from #57.

1968: Avengers #57

Black Panther Bonanza! By Buscema, Buscema, and Buckler

First of all, isn't the magnificent, magisterial, glorious, gorgeous, and altogether amazing Chadwick Boseman the perfect Black Panther?  What a performance, and what a film! 

Now as for comics, who's your favorite delineator of the Black Panther? There've been some great work over the years by many excellent artists, but for my money no one drew a more regal, powerful Panther than John Buscema--though others have come mighty close. 

Below, some classic T'Challa art by Big John and disciples.

Top: John Buscema - Avengers #74 (1970)
Bottom: Sal Buscema - Avengers #78 (1970)
Inker on both: Tom Palmer

Top: John Buscema - Avengers #56 (1968)
Bottom: Rich Buckler - Avengers #106 (1972)