ESPOL was basically first, with BCPL, PL/360, and, as George mentioned, BLISS showing up soon thereafter.
The big question mark in my mind is Algol/W; how well known was it at the time?
Any 360 shop, particularly if it was targeted for teaching students, would likely have had Wirth's compiler. Remember, as BCPL was to CPL, PL/360 was to Algol-W. Unlike BCPL, I don't know of any port of PL/360 outside of the IBM world. Algol-W would later be implemented in C, but that was later after Wirth tried again with Pascal.
Was any consideration for it made?
Only Ken can answer that. My guess is that Algol-W would have failed for the same reasons Pascal ultimately failed. It really was directed at students and lacked many of the tools C had. Many of the issues exposed in Brian's treatise "Why is Pascal not my favorite programming language" also apply to Algol-W.
At the time, BLISS had the advantage of the first "Green Book" style optimizer, so in comparison to the original B and later C compilers, their code generators were almost toys. I believe that the killer for BLISS was DEC's choice to charge $5K per/cpu and to few places were willing to pay it. But as Paul points out BLISS was word-oriented, which, from a technical point of view, made it more difficult to use than C.