Which famous engineer should be on an element14 sticker?

If we are talking engineers rather than scientists, physicists and mathematicians I would add Tommy Flowers.

Although Alan Turing rightly gets a lot of credit for "inventing" computers, it was Tommy Flowers who designed and (with other engineers from the British Post Office) built the first one (Colossus) and delivered it to Bletchley Park in the 1940s. It worked exactly as planned and helped the UK decrypt messages sent using the Germans' Geheimschreiber machine. Although everybody knows about the Enigma machine, the Geheimschreiber offered far greater security than Enigma - and Alan Turing's Bombes were simply not fast enough to decode the messages. The biggest technological advance introduced by Flowers was the use of several thousand electronic valves in a single device, instead of the mechanical relays used by the Bombes. Bletchley Park did not believe that using valves in such numbers would be practical because of reliability but Flowers knew that, as long as they were left running, they would prove to be very reliable, as well as being many times faster than relays. The success of the first Colossus led to another ten being built. After the war, they were all destroyed, along with the plans, and Tommy Flowers has never enjoyed the recognition that he deserved. Ironically, some plans did survive as they had been shared with the US secret services, and those were later used to recreate Colossus. A working replica can be seen in operation now at Bletchley Park.

If we are talking engineers rather than scientists, physicists and mathematicians I would add Tommy Flowers.

Although Alan Turing rightly gets a lot of credit for "inventing" computers, it was Tommy Flowers who designed and (with other engineers from the British Post Office) built the first one (Colossus) and delivered it to Bletchley Park in the 1940s. It worked exactly as planned and helped the UK decrypt messages sent using the Germans' Geheimschreiber machine. Although everybody knows about the Enigma machine, the Geheimschreiber offered far greater security than Enigma - and Alan Turing's Bombes were simply not fast enough to decode the messages. The biggest technological advance introduced by Flowers was the use of several thousand electronic valves in a single device, instead of the mechanical relays used by the Bombes. Bletchley Park did not believe that using valves in such numbers would be practical because of reliability but Flowers knew that, as long as they were left running, they would prove to be very reliable, as well as being many times faster than relays. The success of the first Colossus led to another ten being built. After the war, they were all destroyed, along with the plans, and Tommy Flowers has never enjoyed the recognition that he deserved. Ironically, some plans did survive as they had been shared with the US secret services, and those were later used to recreate Colossus. A working replica can be seen in operation now at Bletchley Park.