If it was me, I would prefer to play in the Championship and live in England as opposed to playing for Spartan and living in Russia. However if it was between England and Holland, I'd go for whoever was offering me the most money.
He wouldn't be guaranteed first team football at Norwich but presumably would get double the wages. He could play Champions League football at Celtic, although not for long, I have no idea what wages are like in the SPL.
Perhaps neither Norwich or Celtic are prepared to offer £1.4 million...