Through experience 14 feet swing gate is good enough. 14 half if you like. Any thing bigger than that dont look good for 20 feet wide house. Gate proportionality too big make your house appear to be small, not grant. Try to balance between practicality vs looks. Also if your front driveway and the outside road is not level you may have little problem positioning your cars. Arm gate will take some space vs the traditional ones which install on the ground. You can forget about folding gate. If you really want an easy parking you can opt for sliding type. You can then take the whole 20 feet opening on either side at a time. Not necessary to have a level gate, you can make it a "m".

you need to look at the road is wide enough when your big gate is swing open for you to enter the house with ease...my area a lot of people which i dont quite understand why they park outside the house when they have space in side the house. Their parking causes difficulty to drive my car into the house if I go for swing type. Therefore i opt for folding...

And with folding type when i have visitor that park in front of my gate, I can still open the gate.

16feet medium car (city, civic) can squeeze in but need to be careful. Bigger car like Camry, Accord are no way. probably need another 1 feet each side.

Just my experience.

I'm looking for gate which does not requires painting for the long run. any recommendation what type of gate i should look for? I'm not interested with the stainless S gate though.

cheers

Stainless still is The best for your option. Alternative can try hot dip galvaniz without paint

slightly more than 90degree

I'd been told by dcmoto that the swing type has some disadv, there won't be any stopper for the gate when closing, the stopper is at the motor itself,  and therefore swing gate might not close perfectly.
He ask me to use the folding instead.  But I don't think I can afford to have this since both folded gate will need another 1 ft each.

sometime we save but end up dont like it or not suitable then what's the point....

I was using a swing gate before and when my gate guy show me the new ones I asked what happen to the center stopper and lock. you can ask them to add the stopper lock in the center. Your swing door will be stopped at the stopper in the center and a metal rod will drop down and lock. new model dont use this but they do add if you want. However, I finally decided to use folding coz I did my new gate wider and hence swing gate will open quite out which is inconvenient to turn into my porch and cant park in front of my house.

yup you do have an issue with folding gate...unless you dont mind the pilar not the same size at each side of the gate.

I dont put dustbin outside coz there are dogs. And in my area, the collector comes quite punctual on alternate days. So we just put out the rubbish in the morning.  My contractor before did advice to "plant" a dustbin metal stand and put the bin on top where dogs cant topple or reach the top. You may want to consider that.

OK, good suggestion, I think I will have to go for this if I want a bigger folding gate opening.

whatever it is please check with your contractor and gate guy....dont forget your letter box and also in case you want 3phase power box (if your house is not on 3 phase now)..

Dcmoto seller claim no problem to pull even a 20' swing gate!