Should we get an EC or resale HDB? ?

You will be eligible as a first timer for CPF Grant when choosing an EC. Both BTOs and ECs are reasonable choices and there is a much better supply of BTOs vs limited supply of ECs in the market now. In fact, there might be only 1 EC that is launching in Punggol this year, and Anchorvale EC either end of this year or next year.

Agree with Hariz to work with your financial advisors or bankers to get a proper assessment of your financial affordability.
Based on your info, you appear to be in the sweet middle income spot to be eligible for an EC with priority as a first timer. No harm visiting the showflat to get a queue number then decide later since there are no penalties if you decided not to book a unit. If you can afford the EC, you might get a good chance to choose a preferred unit vs balloting with more people for BTOs.
Resale upside is indeed usually limited as the first buyers would have harnessed most of the potential gains already. But you have peace of mind without worrying about debt and loans. Depending on your age, if you are young, you have a longer loan tenure to rely on.
Think about what you are looking for in the future, rooms for kids... better lifestyle having a private condo with facilities... to stay in the same place until retirement, etc. the path ahead is dynamic and can change with times so it is important to consider everything in more detail on a longer term plan.
One more thing, you may be eligible under income ceiling for BTO and ECs now. Your income will likely grow again in the next few years and may take that eligibility away. So discuss well with your spouse and focus on the future.. what do you see yourself 5, 10 years down the road. Esp when you have kids.
Should you need further advice on property progression plans, you can feel free to PM me.

The rule of thumb for home affordability is maximum 7X combined annual income. In this case that's 924k.

You can comfortably own the EC as long as you stay employed and do not have a reduction in your earnings during the tenure of the mortgage.

And in this case, though the resale is cheaper, probably bigger, you also have to deal with a shorter lease.

I'm not a property agent, but the EC does look like the better deal.

Another consideration you may have also though, is that a cheaper house, would mean you have more cashflow for other investments. Even though an EC can have capital gains, you're not going to realise it unless you sell and buy a cheaper place in the future.

So if you're investing and can earn a higher annual return than the growth of your home, it may then make sense to take a smaller home and lower your monthly commitment.

Speak to a property agent and a financial advisor at the same time to run through the numbers of both options with you.