The most annoying thing about cheap road bikes is the lever on sora/2300 STIs to shift down a gear. it is "supposed" to be easier to access from the tops but it plain isn't its just awkward in any hand position, and requires a high amount of pressure. Try it out!
With that in mind, first (immediate!) upgrade would be some used tiagra STI that have a proper paddle to shift down.
Second upgrade would be the bargain planet-x al30 wheels 1.7kg at £150 http://www.planet-x-bikes.co.uk/i/q/WPP ... 0_wheelset
So I would buy the cheaper decathlon bike and put the extra money into the upgrades above. You can put the old STIs on ebay for just under retail price about should get £50 back for the unused wheels.
You don't need a triple a compact double is fine unless you are going touring and need to carry extra weight.
With that in mind, first (immediate!) upgrade would be some used tiagra STI that have a proper paddle to shift down.
Second upgrade would be the bargain planet-x al30 wheels 1.7kg at £150 http://www.planet-x-bikes.co.uk/i/q/WPP ... 0_wheelset
So I would buy the cheaper decathlon bike and put the extra money into the upgrades above. You can put the old STIs on ebay for just under retail price about should get £50 back for the unused wheels.
You don't need a triple a compact double is fine unless you are going touring and need to carry extra weight.