In Śvetāmbara tradition, “Ishta Tirthankar” simply means:

• “Your chosen / preferred Tirthankar” for bhakti and daily worship.
• There is no fixed or compulsory Ishta Tirthankar decided by the sect; it is purely personal choice.

Some people naturally feel more devotion towards:

• Mahavir Swami
• Parshwanath Bhagwan
• Shantinath Bhagwan
• Neminath, Adinath, etc.

Any of the 24 Tirthankars can be your Ishta Tirthankar. Śvetāmbara āchāryas clearly teach that:

• All 24 are equally Siddha‑bhagwan in their real form.
• Choosing one as Ishta is only to focus the mind in bhakti, not because that one is “greater” than others.

So, as per Śvetāmbara view:

• Ishta Tirthankar = the Tirthankar you personally choose and love to remember, pray, and meditate upon regularly.
• You are always free to worship and bow to all 24 Tirthankars as well.

If you want, you can also read a related explanation about choosing an Ishta Dev and worship of different Tirthankars here: