#2 Mikel Arteta - Real Sociedad to Everton

Identified as a replacement for Real Madrid bound Danish midfielder Thomas Gravesen, Arteta was a surprisingly successful acquisition at Goodison Park during David Moyes's tenure.
Arteta initially joined on loan on the deadline day of the January window in 2005. Arteta helped Everton finish 4th in the Premier League that season and signed permanently in July 2005 for a minimal fee of £2 million.
During his time in Merseyside, he was named the clubs Player of the Season twice. His creativity and guile were an integral part of Everton's attack and he went on to register 209 appearances for the Toffees before finally joining Arsenal in 2011.
#1 Luis Suarez - Ajax to Liverpool

Joining Liverpool from Dutch side Ajax on 31 January 2011, Suarez's arrival at Anfield was somewhat overshadowed by the £35 million arrival of Andy Carroll a few hours later. But it was the Uruguayan who came for £22.8 million who went to become one of the Reds' best player of the last decade.
Suarez's time at Merseyside was marred with many controversies but it was his on-field performances that would be fondly remembered by the Anfield faithful.
The Uruguayan scored 17 goals in his first season in Merseyside, but it was in the 2013-14 season where he truly exploded, firing in 31 goals to win the Golden Boot and very nearly firing Liverpool to their first ever Premier League title, before leaving for Barcelona the following summer.