OK putting it like for like some +/- based on both being a 600mm wide version
1 they both take 600mm so take the same space
2 a built in does usually look neater
3 a stand alone will have a larger oven (esp if you go down the double
oven route)
4 You could use the same extractor ambove either so pretty much negates
that argument
5 You will generally get 'more' for your money spec wise for a stand alone
6 When you come to sell the house you can take a freestander with you but
a built in is regarded as fixtures anf fittings
7 Again on selling the two rooms that generally sell a house are kitchen
and bathroom so long term investment or short term step on the property
ladder
After thinking thru the above only you can really make the decision, but a couple of other pointers
Now matter how good technology is getting a gas hob is stil more controllable/efficient than an electric one (there are exceptions ie some electric hobs can have built in timers etc now a days but mega bucks)
An electric fan assisted cooker cooks faster and more efficiently cost wise than a gas oven
So if you go gas hob electric oven you get the best of both, and also can still cook if either the gas or electric is off